Automated analytical instrumentation for the imunochemical testing of samples is well known. Typically, a sample of fluid such as human serum, plasma, CSF or urine is combined with one or more prepared liquid reagents and after appropriate specific time periods have elapsed and further reagents added if necessary, one or more characteristics of the mixture is observed to provide an analytical result. Automation of these tests confers advantages over the manual procedures which a laboratory technician has to follow, such as improved accuracy and precision of control of timings, volumes of fluids, and temperatures, leading to improvements in accuracy and repeatability of the testing. In addition, automation of testing can provide results more rapidly and more cost-effectively than manual testing.
Automated clinical analyzers generally provide a means of transporting the reaction mixtures of different test samples between the various operating stations needed to perform the tests. Thus the mixtures are moved between positions at which reagent addition, removal, mixing, washing, incubation and detection are performed, the precise timing and sequence being a function of the type of technology being used to conduct the assay. One such analyzer, the IMx, is sold by Abbott Laboratories. A weakness of this instrument is that the sequence of movement and timing at each station is the same for all samples being analyzed, and once started, each test progresses in sequence through the system. This, combined with the limitation of having reagents stored on the instrument for only one type of analysis, restricts its application to running pre-defined batches of samples, with no flexibility for performing different analyses on the same sample.
Other instruments, such as the SR1 sold by Serono Diagnostics and the Affinity sold by Becton Dickinson (EP-A-223 002) avoid some of these limitations by providing the test specific reagents in a unit-dose pack which incorporates chambers both for storage of the reagents and for performing the test. Such systems permit the individual reaction mixtures to access the various workstations at time intervals which are independent of each other, and can thus process different kinds of tests in any order.
A major disadvantage of these random access systems is the requirement to have individually packaged test specific reagents for each analysis to be performed. Typical unit-dose reagent packs have up to 4 separate reagents provided therewithin, and while seeming convenient for the user, this is a very costly way of providing the reagents due to high packaging costs, excessive volumes of fluids being provided in order to guarantee sufficient for running the test, and relatively high costs of providing refrigerated storage space due to the bulky nature of the packs. Manufacturing and quality control of such packs is necessarily complex, batch homogeneity being difficult to establish and scrap rates can be high.
A feature of these systems is the positioning of the sample/reagent reaction mixture around the periphery of a rotatable carousel, this being the means of transporting the mixtures to the various operating stations. Movement of one mixture to a particular station then displaces all other mixtures at the same time; movement which can then expose them to varying temperatures and other disturbances. Thus, although they are called random access analyzers, processing of each sample is not truly independent of all others. Also, scheduling of tests can become restricted if every one of the test mixtures is moved for each operation of each sample.
It is one objective of the present invention to overcome disadvantages of the above described systems by providing the test specific reagents for a variety of different tests stored in an apparatus unit bulk form, and configuring the sample/reagent reaction mixture transport system such that a chosen material can be accessed for processing in a manner which does not influence the others in any way. Bulk storage of reagents on the instrument not only improves reagent manufacturing efficiency and economics, but allows more reliable storage since the temperature can be controlled on the instrument. By dispensing with the need for unit-dose packs, improved convenience of sample loading can be accommodated by designing the instrument to accept the primary draw tubes, which can be sampled for a variety of different tests to be performed.